The present invention relates generally to an ink cartridge for use with an ink-jet type recording apparatus and, more particularly, to an ink cartridge for use with an ink-jet type recording apparatus which compensates for misalignment of the ink supply port and ink supply needle to stop any ink from leaking.
Ink-jet type recording apparatuses use liquid ink to print recording data. Particularly, an ink-jet type recording apparatus employs an ink cartridge that supplies ink contained therein to the recording head. The ink cartridge is directly connected to the recording head through the use of an ink supply needle mounted on the recording head. Ink is delivered by utilizing a pressure difference between the ink in the recording head and the ink in the ink cartridge, and by capillary forces.
As a result of this construction, the ink cartridge is required to have a structure for connecting the ink cartridge to the ink supply needle. This structure is disposed either on the lower surface of the ink cartridge or below the ink cartridge itself. This arrangement of the connecting structure in turn requires that an appropriate measure be taken to contain leakage of ink from the ink cartridge when the cartridge is connected to the ink supply needle. As has already been disclosed in Japanese Unexamined Patent Publication No. 50-74341, one method of dealing with the leaking of ink which is widely used is to employ a packing having a through-hole and a seal that allows the ink supply needle to be hermetically fitted into this through-hole at the ink supply port of the ink cartridge. With this structure, the ink cartridge can be positioned and retained in contact with the recording head without allowing any ink to leak by inserting the ink supply needle into the through-hole of the packing so as to pierce the seal.
In order to prevent any ink from leaking, the ink supply port provided on the ink cartridge must have a minimal diameter. This design further requires a minimal diameter for the through-hole in the packing that is disposed in the ink supply port. However, if the ink supply needle is not positioned precisely coaxial with the through-hole in the packing disposed in the ink supply port, or if the ink supply needle is not perfectly perpendicular with respect to the packing disposed in the ink supply port, then the ink supply needle will not be centered upon insertion into the through-hole of the packing. As a result, the ink supply needle will be in contact with only a portion of the packing, whereas the remaining portion of the packing will not come in contact with the ink supply needle. Thus, ink will leak from between the ink supply needle and the packing where the ink supply needle does not contact the packing.
This problem of leaking ink also arises from inconsistent positioning tolerances among the multiple ink supply needles in a recording head for a color printer using more than one ink supply needle to supply color inks to a recording head from a plurality of color ink tanks. In many cases, the plurality of color ink tanks is provided as a plurality of compartments in a single tank, so that the spacing between the connecting structures of the ink tank compartment and between the respective ink supply needles is fixed, aggravating the tolerance problem.
In addition, an ink tank must be ventilated in order to equalize pressure differences for the printer to work properly. However, ventilation of an ink cartridge often results in some of the ink evaporating during use, especially if the ink cartridge is used infrequently.
Accordingly, the present invention provides an ink tank with a seal which compensates for inconsistent positioning of ink-supply needles, or inconsistent inclines of ink-supply needles and keeps ink from leaking from the ink supply tank while in use. The present invention also provides an ink tank which is ventilated, but protects against the evaporation of the ink contained therein.